Reinforced frame for a roller skate

ABSTRACT

A frame for skates and the like iwth a structure that includes at least one bearing surface engageable by a boot or the like, and a side flange. One or more ground-engaging members are attached to the frame. The components of the structure of the frame are made of at least two at least partially mutually assembled materials having different mechanical properties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to a frame for gliding sport articlessuch as roller skates, ice skates.

2. Description of Background and Relevant Information

The frames of the aforementioned type are adapted for the linkagebetween one or more gliding members themselves (namely the ice skateblade, wheels or rollers) and the user's foot between which it isinserted.

The frames are therefore generally constituted by a bearing surfacecapable of receiving the athlete's shoe, and by one or two longitudinallateral flanges adapted to receive the wheels, rollers or the skateblade.

They must also have substantial mechanical resistance characteristicswhile being as light as possible in order not to require too substantialefforts from the athlete.

Furthermore, the advanced technology in these gliding sport articles,especially in the case of in-line roller skates, further increases therequirements, which must be met by the skate frames, and which mustreach a compromise between:

an increased mechanical resistance and stability, especially for thespeed skates, but also for the so-called “free ride”, “free style” or“hockey” skates, in order to offer efficiency and an unquestionableresponse in the transmission of movements to the skate by the skater;

a certain flexibility, especially in certain zones of the skate to allowfor an adaptation of the shape of the skate to the path taken,especially on curves at high speeds, but also the dampening of shocksand vibrations,

as light a weight as possible.

Furthermore, it is known that the front wheels are the first to receivethe ground impacts, whereas the rear wheels transmit the most power.

Currently known techniques for making frames do not allow meeting allthese requirements while maintaining a reasonable manufacturing cost.

Indeed, the oldest manufacturing technique consists of making suchframes from folded sheet metal, in a U-shape, as shown in the Germanpatent DE 10 33 569, for example.

Such a construction method, although inexpensive, does not, however,allow obtaining frames with great mechanical resistance except bysubstantially increasing the thickness of the sheet metal and thereforeits weight, and it allows obtaining a certain flexibility in selectedareas even less.

Another commonly used technique consists of making the frames entirelyby molding from synthetic or even metallic materials. The integralmolding offers the advantage of allowing sufficiently varied forms, butfurthermore presents numerous disadvantages, the main disadvantage beingthe impossibility of the compromise sought and cited previously, foreven if the constitutive material of the frame has characteristics ofstiffness, it cannot offer at the same time characteristics offlexibility, except by providing zones that are more or less thickaccording to their function, but this would lead to molds having aburdensome design because it is complicated.

In this field, frames made from composite fibers are also known. Suchframes can actually be made in almost any shape possible, but theirconstruction is extremely expensive and hard to industrialize. Moreover,such frames are certainly very stiff but lack flexibility and aretherefore fragile and uncomfortable.

Finally, U.S. Pat. No. 5,388,846 proposed making a frame for an iceskate or a roller skate from a sectioned metallic bar whose transversesection corresponds to the general section desired for the frame, thefinal shape of the frame being obtained after machining with removal ofmaterial.

Such a construction method is again very expensive, given the machiningtime necessary and the quantity of material that must be removed. Inaddition, it does not allow great freedom with respect to the shape orprofile of the frame, nor in seeking the mentioned compromise.

U.S. Pat. No. 3,086,787 from C. A. Wyche relates to a roller skate withan adjustable length whose stability and stiffness are ensuredregardless of the number of rollers and the distance separating thefront and rear rollers. The skate comprises a support plate bent in aninverted U-shape, preferably made of fairly thin steel on which elementsare slidably mounted for maintaining the heel and tip of the foot. Toeach of the side portions of the support plate, there is welded orscrewed a downwardly extending metal plate, preferably made of hardenedsteel and extending the full length of the skate.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome these drawbacks andto provide an improved frame for gliding sport articles which allowresolving the various problems previously mentioned and, in particular,combining the characteristics of mechanical resistance, adaptability,construction flexibility, lightness and low manufacturing costs.

This object is achieved with the frame according to the invention, whichcomprises at least one bearing surface adapted to receive a shoe and atleast one lateral flange provided with means for attaching at least onegliding member, wherein at least one portion is made of plastic thatcovers, at least partly, a reinforcement having mechanicalcharacteristics different from the plastic portion.

BRIEF DESCRIPTION OF THE DRAWINGS

In any case, the invention will be better understood and othercharacteristics thereof will be shown with the following description;with reference to the attached schematic drawings representing, by wayof non-limiting examples, several frame embodiments, and in which:

FIG. 1 is a side view of a reinforced frame generally representedaccording to an example of the invention;

FIGS. 2-6 are transverse cross-sectional views of a frame according todifferent embodiments;

FIG. 7 is a side view of a frame made according to the embodiment ofFIG. 6;

FIGS. 8-15 are transverse cross-sectional views according to otherembodiments;

FIGS. 16-20 are longitudinal views of a frame according to alternativeembodiments.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, the frame 1 according to the invention is made atleast in part of plastic and is generally presented in the form of twolateral flanges 2 connected together by two platforms 3 and 4 or bootbearing members which give the assembly a substantially U-shapedtransverse section.

Each of these platforms 3 and 4 constitutes a bearing surface capable ofreceiving the athlete's shoe, the latter (not shown) being attached byany known means, especially glue, rivets, screws, etc., but it can alsobe attached in a removable manner by non-permanent connecting means.

It is also noted that the platforms 3 and 4 are distinct and separatedfrom each other by a cutout 5, and are positioned at different levels ofheight, the platform 4 being higher than the platform 3, to take intoaccount the natural position of the athlete, the heel being slightlyelevated. Of course, they could also be positioned at the same level.

Each flange 2 has a straight elongated form, but it can also be slightlybent in an arc of a circle in the longitudinal direction.

At the lower end of each flange, holes 6 are provided for attachingrollers, or as the case may be, a skate blade.

Each hole 6 is made in a cylindrical boss 7 capable of being obtained bydie casting, boring, etc. The holes 6 positioned correspondingly in thetwo flanges 2 are coaxial.

According to the invention, the constituent parts of the previouslymentioned structure constituting the frame 1, namely the bearing surface3 and 4 and the flanges 2, are made from at least two materials ofdifferent mechanical characteristics, at least partially attached ontoor into one another.

In this case, but in a non-limiting way, it is the flanges 2 which, atleast in part, are made of a material different from the rest of thestructure.

Indeed, the invention can relate to other parts of the frame as thiswill be described later.

In the example of FIGS. 1 and 2, the lateral flanges 2 are parallel withrespect to one another to form a “U” with the bearing surface 3 and 4and are made of the same material as the bearing surfaces, but they aredoubled by external reinforcements 8 made of a different materialcapable of modifying the mechanical characteristics of the assembly thusobtained.

For example, the reinforcements 8 are metallic, whereas the rest of thestructure is obtained by molding a plastic material, but it can verywell be imagined that the reinforcements 8 be obtained from a plasticmaterial with predetermined mechanical characteristics, whereas the restof the structure is also made from a plastic material with differentcharacteristics.

The metallic reinforcements 8 are obtained by cutting and stamping, thenattached to the flanges 2 by any means.

According to the invention, the metallic reinforcements 8 are attachedto the flanges 2 by molding when the latter are molded.

Such reinforcements 8 also have the advantage of comprising, at theirlower ends, the bored and threaded boss 7, to allow attaching, withoutany intermediate piece, of the gliding members on a stiff metallic zone,or further on hard plastic where the reinforcements 8 would be made of aloaded plastic rather than a flexible plastic constituting the rest ofthe structure.

Advantageously, the metallic reinforcements 8 comprise, in theirlongitudinal direction, stiffening ribs obtained by stamping, extendingsubstantially along the whole length of the flange 2 and having agenerally bent shape.

Such a characteristic allows, at equal stiffness, dividing the thicknessand therefore the weight of the reinforcement 8 practically in half

Regardless of the example described hereinafter, an improvement of thetorsional and flexional stiffness of the frame is obtained due to thereinforcement elements. Of course, these can be arranged between theinside and the outside of the frame so as to optimize the necessarymechanical characteristics thereof It is also possible to have areinforcement on one side only of the frame, since it is known that themaximum of the forces transmitted by the skater to the wheels passthrough the inside skirt or flange of the frame. That is also whycertain examples envision using different materials between the internalflange and the external flange.

In the embodiment example of FIG. 2, the frame ID comprises bearingsurfaces 3, 4 obtained integrally with parallel lateral flanges 2D,forming a U with the bearing surfaces, through plastic molding includingthrough molding or co-injection, an internal reinforcement 8D embeddedon or in the bearing 3, 4, and made of a metallic material or a plasticmaterial different from the preceding one. Such a construction is, ofcourse, compatible with the bearing surfaces 3, 4 positioned atdifferent levels.

Thus, a structure whose bearing surface alone is stiffened is obtained,whereas the flanges maintain a certain flexibility.

In the examples of the invention shown in FIGS. 3-7, the frame 1E, 1F,1G, 1H is generally constituted by a bearing surface 3, 4, and twolateral flanges 2E, 2F, 2G, 2H, parallel with respect to one another andforming a U with the bearing surface, this structure being obtained bymolding a plastic material around at least one reinforcement 8E, 8F, 8G,8H, made of metal or a plastic material different from the first,arranged inside the flanges.

More particularly, according to FIG. 3, the reinforcement 8E forms a Uextending, on the one hand, inside the bearing plane 4, and, on theother hand, inside the lateral flanges 2E by their parallel arms, theend of the latter being positioned on this side of the end parts of theflanges 2E which are bored with holes 6 and threaded to ensure theattachment of the gliding members.

However, according to the alternative embodiment shown in FIG. 4, thereinforcement 8F forms a U extending, on the one hand, inside thebearing plane 4, and, on the other hand, inside the lateral flanges 2Fby their parallel arms, the end of the latter extending beyond the endparts of the flanges 2F which are bored with holes 6 and threaded toensure the attachment of the gliding members. This last solution offersthe advantage of creating reinforcements at the level of the holes 6.

According to the example of FIG. 5, the frame 1G is constituted of twoparts, the first part integrating a reinforcement 8G molded in a portionof the bearing surface 4 and a flange 2G, generally perpendicular to theportion of the bearing surface 4, the second part comprising acomplementary portion of the bearing surface 4 and a second flange 2G′with no reinforcement, means for connecting the two parts 2G, 2G′ of theframe 1G being arranged at the level of the bearing surface 4.

The means for connecting these two frame parts are constituted by anextension 8Ga of the reinforcement 8G of the first frame part extendingbeyond its part of the bearing surface 4 so as to exit freely therefromin order to cooperate with a corresponding housing 4 b provided in theother portion of the bearing surface 4 of the second part of the frame1G.

The immobilization of the reinforcement part 8Ga in the housing 4 b isdone by any means, in this case by a screw 11. The advantage of such anembodiment is that the frame can be made more simply in two parts andthat the assembly of these two parts can easily be obtained by insertingone of the parts.

In the frame 1H, according to the example of FIG. 6, the reinforcement8H forms a U extending in an apparent way on the internal surfaces ofthe U formed by the parallel arms of the flanges 2H, and by the bearingplane 4 connecting them.

According to this same example, at least one of the lateral flanges 2Hcomprises a longitudinal window 10 for visualizing the reinforcement 8H.

It is noted that the reinforcements can also be made of compositematerials (glass fibers, carbon fibers, etc.).

In the example of FIG. 8, the frame 11 comprises reinforcements 81constituted by two distinct planar elements extending inside the lateralflanges 21 and whose ends extend beyond the end portions of the flangespierced with holes 6.

According to the example of FIG. 9, the frame IJ comprises areinforcement 8J constituted by a single planar element extending insidea single lateral flange 2J and whose upper end is bent perpendicularlytowards the outside to locally reinforce the bearing plane 3, 4, andwhose lower end extends beyond the end portion of the flange 2J piercedwith a hole 6.

It is noted that the essential difference between the example of FIG. 9and FIG. 8 lies in the asymmetry of that of FIG. 9. However, in the twocases, the reinforcements 8I and 8J are metallic, whereas the rest ofthe structure, and especially the flanges 2I and 2J, are plastic.

According to the example of FIG. 10, the frame 1K comprises areinforcement 8K constituted by an orthogonal element, one end of whichextends inside one of the flanges 2K, beyond its end part pierced withholes 6, and another part extends inside the bearing surface 3, 4. Also,in this case, the reinforcement 8K is metal, whereas the rest of thestructure is plastic.

According to the example of FIG. 11, the frame 1L comprisesreinforcements 8L constituted by two distinct elements extending insidethe flanges on either side of the end holes 6 of the flanges 2L. In thiscase, the reinforcements 8L are made of hard plastic, whereas the restof the structure is made of more flexible plastic. They can also bemetallic.

According to the example of FIG. 12, the frame 1M comprises areinforcement 8M, itself constituting one of the structure flanges, andextending perpendicularly to constitute a lower part of the bearingplane 3, 4, cooperating with an upper part of the same plane whichextends perpendicularly to constitute the other flange, the structurebeing made by co-injection of two different plastic materials. In thiscase, the reinforcement 8M constituting one of the flanges is made of arelatively rigid plastic, and the rest of the structure is made of amore flexible plastic.

According to the example of FIG. 13, the frame IN differs essentiallyfrom the preceding ones in that the flanges 2N are made of a rigidplastic material that does not require a reinforcement, but a flexibledampening part 8N is made of a “foamed” plastic layer and molded ontothe bearing plane 3, 4 of the structure.

According to the example of FIG. 14, the frame 1P comprisesreinforcements 8P constituted by two distinct elements extending partlyinside the shortened flanges 2P and partly outside the latter toconstitute their end pierced with holes 6. In this case, thereinforcements 8P are metallic, whereas the rest of the structure isplastic.

According to the example of FIG. 15, the frame 1Q comprises areinforcement 8Q constituted by a U-shaped element covering theshortened flanges 2Q and the bearing plane 3, 4, and extending beyondthe flanges to constitute the end of the latter pierced with holes 6. Inthis case, the reinforcements 8Q are made of a relatively rigid plastic,whereas the flanges 2Q and the bearing plane 4 are made of a moreflexible plastic.

According to another essential characteristic of the invention, thereinforcements 8, according to all the previously described examples,extend, as needed, in a variable way, along the transverse axis and/orlongitudinal axis of the structure.

Thus, according to the example of FIG. 16, the flanges 2F, 2G, 2H, 2I,2J, 2K are provided with at least one lateral reinforcement 8F, 8G, 8H,8I, 8J, 8K constituting a zone A and extending partially into onecorresponding flange along the longitudinal axis, so as to reinforce thestructure at the level of at least one hole 6 of the wheel. In thiscase, this lateral reinforcement extends over the quasi-totality of theflange and all of the holes 6.

However, according to the example of FIG. 17, which in fact shows twopossible examples, at least one lateral reinforcement B and C extendspartially into one corresponding flange along the longitudinal axis, soas to reinforce the structure at the level of at least one hole 6 of awheel. It is noted that in the case of a reinforcement covering a zoneB, the latter reinforces a corresponding zone covering two holes 6,whereas according to another case illustrated by a reinforcement whichwould be constituted by the zones B and C, the reinforcement wouldreinforce the structure in the corresponding zones, but also at thelevel of three of the holes 6 of the wheels.

According to the example of FIG. 18, two rigid reinforcements D, F areintegrated in at least one of the flanges, reinforcing the structure atthe level of the wheels and separated in the longitudinal direction by acomplementary intermediate element E made of a relatively flexiblematerial constituting an elastically deformable zone of the frameextending over its whole height.

According to the example of FIG. 19, a rigid reinforcement G isintegrated in at least one of the flanges, reinforcing the structuretowards the rear and extending beyond the ends of the flanges piercedwith holes and generally constituting the bearing plane 3, 4, acomplementary end element H made of a more flexible materialconstituting the front of the structure and also extending beyond theend holes of the flanges.

According to a last embodiment example shown in FIG. 20, a reinforcementI made of a relatively rigid material is integrated in at least one ofthe flanges, and has an upper cutout in which, in the longitudinaldirection, a complementary intermediate element J made of a relativelyflexible material is integrated, which constitutes an elasticallydeformable zone extending in a corresponding upper zone of the frame.The reinforcement I and the complementary intermediate element J willnot necessarily be made of different materials. In this example, severalintermediate elements distributed longitudinally over the frame can alsobe envisioned.

The rigid reinforcement I comprises at the lower end of the cutout, inwhich the soft element J is integrated, a recess K constituting aflexion zone of the frame.

Of course, all combinations of materials can be envisioned regardless ofthe previously described examples. Likewise, the distribution ofdifferent materials, as much in the longitudinal direction as in thetransverse direction, can be envisioned.

What is claimed is:
 1. A roller skate frame comprising: a longitudinallyextending boot-supporting structure comprising a front platform and arear platform, said front platform comprising a front boot-supportingsurface and said rear platform comprising a rear boot-supportingsurface, said front and roar boot-supporting surfaces beinglongitudinally spaced apart; a par of laterally spaced-apartlongitudinally extending flanges, said flanges extending downwardly fromsaid front platform and from said rear platform and integrally formedtherewith, said flanges extending longitudinally between said frontplatform and said rear platform, at least said pair of flangescomprising a plastic material; and a single reinforcement member forsaid plastic material, said single reinforcement member being at leastpartially molded within or onto said plastic material of each of saidpair of flanges, said reinforcement member being configured to support aplurality of longitudinally spaced apart wheel axles.
 2. A frameaccording to claim 1, wherein: said reinforcement member is at leastparty molded within said flanges by co-injection of two differentplastic materials.
 3. A frame according to claim 2, wherein: said pairof lateral flanges are substantially parallel, said front platform andsaid lateral flanges forming a U-shape, and said rear platform and saidlateral flanges forming a U-shape; said reinforcement member itselfconstitutes one of said pair of lateral flanges of the frame and extendssubstantially perpendicularly to constitute a lower part of at least oneof said front and rear platforms which cooperates with an upper part ofsaid one of said front and rear platforms, said reinforcement memberfurther being extended substantially perpendicularly to constitute asecond of said pair of lateral flanges.
 4. A frame according to claim 1,wherein: said reinforcement member is metallic and a remainder of theframe is plastic.
 5. A frame according to claim 4, wherein: at least oneof said pair of lateral flanges includes a longitudinal window forextending from an outer surface of said one of said lateral flanges tosaid reinforcement member for viewing said reinforcement member.
 6. Aframe according to claim 1, wherein: said reinforcement member ismetallic, said reinforcement member being made by cutting and stamping.7. A frame according to claim 6, wherein: said reinforcement membercomprises a lower portion provided with a bored and threaded boss,thereby being configured to support said plurality of longitudinallypaced apart wheels.
 8. A frame according to claim 6, whet: said pair oflateral flanges are substantially parallel, said front platform and saidlateral flanges forming a U-shape, and said rear platform and saidlateral flanges forming a U-shape; said reinforcement member isconstituted by a U-shaped element, said reinforcement member including abase covering at least one of said front and rear platforms and havingdownwardly extending shortened flanges, said lateral flanges of theframe extending downwardly beyond said shortened flanges of saidreinforcement member, said lateral flanges of the frame having holesextending therethrough beneath said shortened flanges of saidreinforcement member, said holes comprising means for supporting saidplurality of spaced apart wheel axles.
 9. A frame according to claim 1,wherein: said reinforcement member comprises at least one stiffeningrib.
 10. A frame according to claim 1, wherein: said pair of lateralflanges comprise a pair of substantially parallel lateral flanges, atleast one of said front and rear platforms being formed integrally withsaid par1liel lateral flanges, said parallel lateral flanges and said atleast one of said front and rear platforms forming a U-shape by moldingof a plastic material, covering said reinforcement member by molding orco-injection, said reinforcement member being metallic or a plasticdifferent from said plastic, embedded onto or into said at least one ofsaid front and rear platforms.
 11. A frame according to claim 1,wherein: said pair of lateral flanges are substantially parallel, saidlateral flanges and at least one of said front and rear platformsforming a U-shape, said pair of lateral flanges and said at least one ofsaid front and rear platforms being made by molding or co-injection ofsaid plastic around said reinforcement member, said reinforcement memberbeing made of metal or a plastic different from said plastic, arrangedinside or outside said flanges.
 12. A frame according to claim 11,wherein: each of said lateral flanges includes a threaded hole forattaching respective ones of said wheel axles; said reinforcement memberhas a U-shape extending within said at least one of said front and rearplatforms, beneath said surface of said one of said front and rearplatforms, and inside of said lateral flanges, said reinforcement memberhaving ends within said lateral flanges, said ends of said reinforcementmember located above said threaded holes of said lateral flanges.
 13. Aframe according to claim 11, wherein: said reinforcement member has aU-shape extending within said at least one of said front and rearplatforms, beneath said surface of said one of said front and rearplatforms, said U-shape of said reinforcement member including legsextending downwardly inside of said lateral flanges; and a threaded holeextending through each of said lateral flanges and through each of saidlegs of said U-shape of said reinforcement member for attaching arespective one of said plurality of wheel axles.
 14. A frame accordingto claim 11, wherein: said reinforcement member forms a U-shapeextending on internal surfaces of said U-shape formed by said lateralflanges and said one of said front and rear platforms.
 15. A frameaccording to claim 11, wherein: said reinforcement member is constitutedby a single planar element extending inside a single lateral flange,said single planar element having an upper end bent perpendicularlytowards the outside of the frame to locally reinforce a respective bootsupporting surface of at least one of said front and rear platforms,said single planar element having a lower end extending beyond an endpart of said flange pierced with a hole.
 16. A frame according to claim1, wherein: said reinforcement member does not extend laterally outsideof either of said flanges.
 17. A roller skate frame comprising: alongitudinally extending boot-supporting structure comprising a frontplatform and a rear platform, said front platform comprising a frontboot-supporting surface and said rear platform comprising a rearboot-supporting surface, said front and rear boot-supporting surfacesbeing longitudinally spaced apart; a pair of laterally spaced-apartlongitudinally extending flanges, said flanges extending downwardly fromsaid front platform and from said rear platform and integrally formedtherewith, said flanges extending longitudinally between said frontplatform and said rear platform, at least said pair of flangescomprising a plastic material; and a pair of reinforcement members forsaid plastic material, each said reinforcement member being at leastpartially molded within or onto a respective one of said plasticmaterial of each of said pair of flanges, each said reinforcement memberbeing configured to support a plurality of longitudinally spaced apartwheel axles.
 18. A frame according to claim 17, wherein: said pair ofreinforcement members are at least partially molded within or onto saidflanges by co-injection of two different plastic materials.
 19. A frameaccording to claim 18, wherein: said pair of lateral flanges aresubstantially parallel, said front platform and said lateral flangesforming a U-shape, and said rear platform and said lateral flangesforming a U-shape; said pair of reinforcement members themselvesconstitute said pair of lateral flanges of the frame and extendsubstantially perpendicularly to constitute a lower part of at least oneof said front and rear platforms which cooperates with an upper part ofsaid one of said front and rear platforms.
 20. A frame according toclaim 17, wherein: said pair of reinforcement members are metallic and aremainder of the frame is plastic.
 21. A frame according to claim 20,wherein: at least one of said pair of lateral flanges includes alongitudinal window for extending from an outer surface of said one ofsaid lateral flanges to a respective one of said reinforcement membersfor viewing said respective reinforcement member.
 22. A frame accordingto claim 17, wherein: said pair of reinforcement members are metallic,said reinforcement members being made by cutting and stamping.
 23. Aframe according to claim 22, wherein: each of said pair of reinforcementmembers comprises a respective lower portion provided with a bored andthreaded boss, thereby being configured to support said plurality oflongitudinally spaced apart wheels.
 24. A frame according to claim 22,wherein: said pair of lateral flanges are substantially parallel, saidfront platform and said lateral flanges forming a U-shape, and said rearplatform and said lateral flanges forming a U-shape; said pair ofreinforcement members are part of a U-shaped reinforcement element, saidU-shaped reinforcement element including a base covering at least one ofsaid front and rear platforms and having downwardly extending shortenedflanges, said lateral flanges of the frame extending downwardly beyondsaid shortened flanges of said pair of reinforcement members, saidlateral flanges of the frame having holes extending therethrough beneathsaid shortened flanges of said pair of reinforcement members, said holescomprising means for supporting said plurality of spaced apart wheelaxles.
 25. A frame according to claim 17, wherein: at least one of saidreinforcement members comprises at least one stiffening rib.
 26. A frameaccording to claim 17, wherein: said pair of lateral flanges comprise apair of substantially parallel lateral flanges, at least one of saidfront and rear platforms being formed integrally with said parallellateral flanges, said parallel lateral flanges and said at least one ofsaid front and rear platforms forming a U-shape by molding of a plasticmaterial, covering said reinforcement members by molding orco-injection, said reinforcement members being metallic or a plasticdifferent from said plastic, embedded onto or into said at least one ofsaid front and rear platforms.
 27. A frame according to claim 17,wherein: said pair of lateral flanges are substantially parallel, saidlateral flanges and at least one of said front and rear platformsforming a U-shape, said pair of lateral flanges and said at least one ofsaid front and rear platforms being made by molding or co-injection ofsaid plastic around said pair of reinforcement members, said pair ofreinforcement members being made of metal or a plastic different fromsaid plastic, arranged inside or outside said flanges.
 28. A frameaccording to claim 27, wherein: each of said lateral flanges includes aladed hole for attaching restive ones of said wheel axles; said pair ofreinforcement members being part of a U-shape, a part of said U-shapeextending within said at least one of said front and rear platforms,beneath said surface of said one of said front and rear platforms, andinside of said lateral flanges, said pair of reinforcement membershaving ends within said lateral flanges, said ends of said reinforcementmembers located above said threaded holes of said lateral flanges.
 29. Aframe according to claim 27, wherein: said pair of reinforcement membersbeing part of a U-shape, a part of said U-shape extending within said atleast one of said front and rear platforms, beneath said surface of saidone of said front and rear platforms, said U-shape of said reinforcementmembers including legs extending downwardly inside of said lateralflanges; and a threaded hole extending through each of said lateralflanges and through each of said legs of said U-shape of saidreinforcement members for attaching a respective one of said pluralityof wheel axles.
 30. A frame according to claim 27, wherein: the frame isconstituted of two separable parts, a first of said two partsintegrating said reinforcement members, said reinforcement members beingmolded in a first portion of at least one of said front and tarplatforms and one of said lateral flanges, a second of said two partcomprising a complementary second portion of said at least one of saidfront and rear platforms and a second of said lateral flanges, saidsecond of said lateral flanges having no reinforcement, a means forconnecting said first and said second of said two parts of said framebeing arranged at the level of said at least one of said front and rearplatforms.
 31. A frame according to claim 30, wherein: said means forconnecting said two parts are constituted by an extension of at leastone of said reinforcement members of said first part extending beyondsaid first portion of said at least one of said front and rear platformsso as to extend freely therefrom to cooperate with a correspondinghousing positioned in said second portion of said at least one of saidfront and rear platforms of said second part of the frame.
 32. A frameaccording to claim 27, wherein: said pair of reinforcement members formspart of a U-shape extending on internal surfaces of said U-shape formedby said lateral flanges and said one of said front and rear platforms.33. A frame according to claim 27, wherein: said pair of reinforcementmembers extend inside of said lateral flanges, said reinforcementmembers having ends extending beyond end parts of said lateral flangespierced with holes, said holes comprising means for supporting saidplurality of longitudinally spaced apart wheel axles.
 34. A frameaccording to claim 27, wherein: said reinforcement members extend partlyinside of said flanges and partly outside of said flanges to form endsof said flanges, said ends of said flanges having holes extendingtherethrough, said holes comprising said means for attaching saidplurality of longitudinally spaced apart wheels.
 35. A frame accordingto claim 17, wherein: said reinforcement members extend only in asubstantially vertical direction.
 36. A frame according to claim 17,wherein: said reinforcement members do not extend laterally outside ofeither of said flanges.
 37. A frame according to claim 17, wherein: saidreinforcement members reinforces only said flanges.
 38. A frameaccording to claim 17, wherein: said lateral flange are substantiallyparallel, at least one of said front and rear platforms and said lateralflanges forming a U-shape; a hole in a lower end of each respective oneof said lateral flanges is provided for supporting said plurality oflongitudinally spaced apart wheels; said reinforcement members extendinside respective ones of said lateral flanges, on either side of saidholes of said lateral flanges.
 39. A frame according to claim 17,wherein: said pair of reinforcement members extend in a variable waytransversely and/or longitudinally of the frame.
 40. A frame accordingto claim 39, wherein: holes are provided, extending through said lateralflanges, for securing said plurality of wheel axles; each of saidlateral reinforcement members extends longitudinally partially along acorresponding one of said lateral flanges, so as to reinforce the frameat at least one of said holes.
 41. A frame according to claim 39,wherein: at least one of said front and rear platforms, together withsaid lateral flanges, form a U-shape; holes are provided through saidlateral flanges for attaching said plurality of wheel axles; saidreinforcement members comprise two rigid integrated reinforcements,reinforcing the frame in an area of said holes, said two rigidintegrated reinforcements being separated longitudinally by acomplementary intermediate element made of a relatively flexiblematerial constituting an elastically deformable zone of the frameextending over an entirety of a height of the frame.
 42. A frameaccording to claim 39, wherein: at least one of said front and rearplatforms, together with said lateral flanges, form a U-shape; holes areprovided through said lateral flanges for attaching said plurality ofwheel axles; said reinforcement members comprise two rigid integratedreinforcements, reinforcing the frame in a rear portion of the frame andextending beyond ends of said holes of said late flanges and generallyconstituting said at least one of said front and rear platforms, acomplementary end element made of a more flexible material constitutinga front of the frame and also extending beyond said end holes of saidlateral flanges.
 43. A frame according to claim 39, wherein: at leastone of said front and rear platforms, together with said lateralflanges, form a U-shape; holes are provided through said lateral flangesfor attaching said plurality of wheel axles; said reinforcement memberscomprise two reinforcement members made of a relatively rigid materialand integrated in said lateral flanges, said reinforcement membershaving at least one upper cutout, a complementary intermediate elementmade of a relatively flexible material being longitudinally integratedin the frame, said intermediate element constituting an elasticallydeformable zone extending in a corresponding upper zone of the frame.44. A frame according to claim 43, wherein: each of said rigidreinforcement members comprises, at a lower part of said cutout, arecess constituting a flexion zone of the frame.